what is space weather?

Space
weather describes the interaction between
the Sun and Earth. Storms on the Sun
can produce bursts of charged particles.
These shoot out into space, and sometimes
end up hitting the Earth. The effects of
solar storms can be as beautiful as an aurora,
or can cause damage to satellites and
health risks to astronauts and aircraft
crews. Alex and Steve here, we'll tell
you more.

Our modern lifestyle depends heavily on space technology, for example for TV and mobile phone communications. We cannot prevent solar storms, but we can monitor the Sun and give some warning when stormy weather is approaching the Earth. Hopefully, appropriate action can be taken to limit any damage.

What is a solar storm?

A solar storm is a sudden burst of very fast charged particles from the Sun. It could be the result of a solar flare or a coronal mass ejection (CME) or both.

Here is a movie of a CME shooting
out from the Sun and showing the "snowstorm"
of energetic particles which hit SOHO.

What is a space storm?

The wind on Earth is always changing; sometimes it's a gentle breeze, at other times it can be blowing a gale. In the same way, the Sun's wind varies a lot. The solar wind normally races along at about 450 km/s, but it can gust at up to 1,700 km/s or more if there is a powerful coronal mass ejection passing by. This is what space weather experts call a space storm.

What is a geomagnetic storm?

A geomagnetic storm is a disturbance in the Earth's magnetic field. This can be caused by sudden changes in the solar wind. These could be caused by a solar flare, coronal mass ejection or by a shock wave in the solar wind.

The wind blowing out from the Sun reaches the Earth, and thanks to the magnetic field the Earth stays protected.